1. Field of the Invention
The present invention relates to an optical disc driving apparatus, and more particularly, relates to an optical disc driving apparatus for defining determination factors which have an effect on land pre-pit signal detection efficiency, and a land pre-pit detection method using the same.
2. Related Art
In general, when an optical disc, such as a digital versatile disc (DVD)-R and DVD-RW, is manufactured, a land pre-pit (LPP) is formed on a land to represent location information of the optical disc. The land pre-pit contains address information to identify any location on an unrecorded disc.
A general optical disc driving apparatus is then employed to detect the land pre-pit formed on the optical disc to acquire the address information, and to perform a variety of control operations with respect to recording or reproducing of the optical disc on the basis of the land pre-pit information.
FIG. 1 illustrates a typical push-pull signal into which a wobble signal, a land pre-pit signal and a noise signal are mixed. The push-pull signal which corresponds to reflected-light information through the optical disc, is obtained from the optical disc by the optical disc driving apparatus in order to acquire the land pre-pit information. Referring to FIG. 1, the push-pull signal is formed based on a composite of a wobble signal, a land pre-pit signal and a noise signal. Typically, a balance level (B) and a slice level (S) of the push-pull signal serve as major determination factors of the land pre-pit signal.
When the land pre-pit information is to be detected, a fixed balance level and slice level are applied considering a location and shape of the land pre-pit according to the optical disc manufacturer. However, a land pre-pit error may occur. The land pre-pit error is an error in which noise components can be misjudged as the land pre-pit actually pitted on an optical disc, particularly when the noise components occur during the detection of the land pre-pit.
In addition, when a pre-pit mark is formed on a groove track which is close to a land in which a pre-pit is pitted, the balance level and the slice level need to be adaptively defined in consideration of physical conditions of the optical disc in order to prepare for the case where a power voltage for forming the pre-pit mark exceeds a proper power voltage, or where the number of re-recording operations exceeds a predefined limit.
According to conventional error test techniques, all of the balance levels and slice levels of the optical disc need to be individually tested in order to determine an adequate balance level and slice level.
FIG. 2 is a flowchart of a conventional error test method for individually defining a balance level and a slice level of an optical disc. Referring to FIG. 2, a balance level (B) and a slice level (S) are set to respective initial values (Bi, Si) at block #1. Next, whether a land pre-pit error occurs is determined by comparing a land pre-pit decoding address with a reference value at block #2. Accordingly, in the case where the land pre-pit is not adequately detected, that is, the case where the land pre-pit error occurs, the balance level (B) is first rearranged in a predetermined order at block #3, and then the slice level (S) is rearranged on the basis of the rearranged balance level at block #4. After the rearranged balance level and slice level are applied, whether an error with respect to the land pre-pit signal occurs is determined at block #5. If the error occurs, whether the slice level (S) is below the last value (n) in a predetermined order is determined at block #6. If the slice level (S) is below the last value (n), the slice level (S) on the basis of the rearranged balance level (B) is continuously rearranged within a range of the last value (n) in order to test the error. If the error continuously occurs during this test, whether the above arranged balance level (B) is below the last value (m) is determined at block #7. If the balance level (B) is below the last value (m), the balance level (B) is secondly rearranged in a predetermined order at block #3. Subsequently, the slice level (S) on the basis of the secondly rearranged balance level (B) is continuously rearranged in order to test the error. This error test is continuously performed within a range of the last value (m) of the balance level (B).
On the other hand, if the error continuously occurs even when the balance level (B) and the slice level (S) are respectively rearranged within the range of the last values (n, m), the error occurrence due to physical damage of the optical disc or the like is confirmed at block #8.
However, the above-mentioned error test method is applied to the optical disc with respect to all applicable balance levels and slice levels. As a result, the error test can require a significant amount of time to complete the testing as a range of the balance level and slice level increases. Therefore, it is difficult to apply the conventional error test method to an optical disc driving apparatus which is operated in real-time.